Joint sitting is called in the following situation:
1. Bill has been passed by one House and transmitted to the other House and it is rejected by the other House
2. Both houses have finally disagreed as to the amendments to be made in the Bill
3. More than 6 months elapse from the date of the reception of the Bill by the other House without the Bill being passed by it.
Please note that if there is a deadlock between the two houses on a Constitution amendment Bill, there cannot be a joint sitting. In case of Money bills, the rejection of Rajya Sabha is immaterial.